Monday, September 24, 2012

Question by Kiwikahuna: Living organisms convert relatively simple food molecules into a complex structure as they grow.? Living organisms convert relatively simple food molecules into a complex structure as they grow. Is this a violation of the second law of thermodynamics. Please explain. (20/25) thank you!

Best answer:

Answer by amansscientiaeNo. The second law of thermodynamics is the definition of temperature. It also says that heat, ALL BY ITSELF or SPONTANEOUSLY, only flows from hot to cold. That is all the second law says. Read it for yourself:

“Heat cannot spontaneously flow from a material at lower temperature to a material at higher temperature. – Version of the second law according to Clausius”

It does not say anything else, even if it is used in its fancy version with “entropy” and such. In physics you learn the almost trivial mathematical equivalence proofs between this version and the “entropy” versions.

As you probably know, your refrigerator makes heat flow from cold to hot. And it does so without violating the second law of thermodynamics. That’s because the heat does not do this all by itself. It has help from an electric motor. Turn the electricity off, the second law kicks in and the food goes bad.

In nature the help comes from the sun or chemical energy sources. Same thing… second law does not apply because its preconditions (… spontaneously…) do not apply.